We have entered an age in which various medical conditions are treatable based on implantation inside a patient of a special device or system. For example, cochlear implants are electronic systems designed to provide useful hearing and improved communication ability to individuals who are profoundly hearing impaired and unable to achieve speech understanding with conventional hearing aids. A typical system includes an implantable stimulator containing electronic circuitry, a coil for power and information transfer, and a stimulation electrode array which is inserted into the inner ear (and perhaps a counter electrode).
FIG. 1A shows a side view and FIG. 1B shows an elevated bottom perspective view of one specific example of an implantable device 100 having a convex element, in this case, a portion of a cochlear implant system. The implantable device 100 includes a coil housing 101 containing receiving coils for receiving a power and/or data signal from an external transmitting coil (not shown). Attached to the coil housing 101 is a stimulator housing 102, which in the case of a cochlear implant system contains modules for developing an electrode stimulation signal for stimulating cochlear nerve tissue. Centered within the coil housing 101 is a convex element 103, which in the case of a cochlear implant system would typically be a magnet housing containing a positioning magnet that coordinates with a corresponding magnetic element in the external transmitting coil arrangement to hold it in a proper operating position for transferring the signal across the skin into the receiving coils. Also connected to the stimulator housing 102 as an electrode lead 104 which in the case of a cochlear implant system connects to an electrode array (not shown) that applies the stimulation signal to the cochlear nerve tissue.
Currently, a surgeon implanting a device with a convex element uses a surgical spreader device to lift a skin flap including the periosteum and then determine and mark the location to provide a recess in the bone structure to accommodate the convex element. Once the location is marked, a drill can be used to drill a recess into the bone at the marked location.